CVE-2026-110871

Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service

State: Published
Severity: 7.1 High
Published: Oct 14, 2026
Updated: Oct 20, 2026
Reserved: Oct 14, 2026

Description

Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	VulnCheck
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H	VulnCheck

Weaknesses

CWE-400 Uncontrolled Resource Consumption

Affected Products

Product	Versions
nodemailernodemailer	3.0.0 to before 10.0.10Affected 10.0.10Not affected

References

GitHub Security Advisory (GHSA-39m8-27wv-hr27)vendor-advisory
VulnCheck Advisory: Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Servicethird-party-advisory

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